China has just endured its hottest summer on record, marked by deadly swings between extremes, from floods that killed 44 in Beijing to blistering temperatures across the northeast.

China’s National Climate Center said average temperatures from June to August reached 22.31 degrees Celsius, the highest since records began in 1961. The heat drove millions to riverbanks, shopping malls and even underground air-raid shelters, while air conditioner sales in the Northeast surged as much as ninefold.

In Mohe, China’s northernmost city and a popular summer retreat, guesthouse owners scrambled to install AC units as heatwaves dampened bookings. To ease the shortage, major AC brands dispatched 100,000 units and more than 3,000 technicians from across the country to “rescue” the northeast.

China’s scorching summers are often driven by a subtropical high-pressure system that traps hot air, a phenomenon known as the “heat dome effect,” according to Zhang Tao, chief forecaster at the National Meteorological Center.

China endured its warmest decade on record from 2012 to 2021, and since then average summer temperatures have kept climbing. A new high was set in 2022, then broken again in both 2024 and 2025, official data show.

This year’s extreme heat was compounded by a north-south climate flip: the traditionally arid north was hit by flooding, while the south turned unusually dry. In Beijing, a rare deluge killed 44 people, left nine missing, and damaged 24,000 homes.

Elsewhere, sudden reversals struck too. In central China’s Henan province, drought-control measures after a dry July gave way to the highest-level flood alerts after heavy rains in early August. The northwestern Gansu province saw a similar swing, according to domestic media outlet Southern Weekly.

Xu Xiaofeng, former deputy director of the China Meteorological Administration, told Southern Weekly that even non-record rainfall can easily trigger landslides after prolonged drought. “Rapid change in itself is highly destructive,” he said.

A study published in Nature Communications in April warned that by as early as 2028, the world could face an even greater risk of climate “whiplash” — when weather rapidly oscillates between extremes.

Cheng Tat-Fan, a postdoctoral researcher at the Hong Kong University of Science and Technology and the study’s first author, explained that such shifts “will significantly shorten response times…catching societies off guard unless adaptation measures are in place.”

Editor: Marianne Gunnarsson.

(Header image: Pedestrians shield themselves from the scorching sun in Shanghai, July 1, 2025. VCG)